Transcript Change - hvonstorch.de

Biologische Anstalt Helgoland
18. September 2012
Long-term
monitoring and the
perspective of
detection and
attribution of
long-term change
Hans von Storch and Kai Wirtz
Institute of Coastal Research
Helmholtz-Zentrum Geesthacht
Germany
Change !
Change is all over the place,
Change is ubiquitous.
What does it mean?
Anxiety; things become more extreme, more dangerous; our
environment is no longer predictable, no longer reliable.
Change is bad; change is a response to evil doings by egoistic
social forces. In these days, in particular: climate change caused
by people and greedy companies.
Change !
Change is all over the place,
Change is ubiquitous.
What does it mean?
There are other perceptions of change: it provides opportunities; it is
natural and integral part of the environmental system we live in.
The environmental system is a system with enormous many degrees
of freedom, many non-linearities – is short: is a stochastic system,
which exhibits variations on time scales without an external and
identifiable “cause”. (Hasselmann’s “Stochastic Climate Model”)
Assessing change
First task: Describing change
Second task: “Detection” - Assessing change if consistent with natural
variability (does the explanation need invoking external causes?)
Third task: “Attribution” – If the presence of a cause is “detected”,
determining which mix of causes describes the present change best
First task: Describing change
Observed values depend on the immediate environment of the
location where the observation is made. This environment is subject
to gradual and abrupt changes. Therefore such data often do not only
reflect changes of the statistics but also other factors, such as
observation method, practice, location, analysis method …
Inhomogeneity is a key constraint, which is usually overseen by nonexperts. Improved instruments and analysis introduces into data
records such inhomogeneities (and thus, false signals); therefore
satellite data as well as re-analyses are in most cases unsuitable for
the assessment multi-decadal change
Example of inhomogeneous data
Wind speed measurements
SYNOP Measuring net (DWD)
Coastal stations at the German Bight
Observation period: 1953-2005
This and the next 3 transparencies:
Janna Lindenberg, HZG
Page 6
Inhomogeneity of wind data
1.25 m/s
Page 7
Inomogeneity of wind data
Page 8
The increase in damages related to extreme
weather conditions is massive – but is it because
the weather is getting worse?
Losses from Atlantic Hurricanes
“Great Miami”, 1926, Florida, Alamaba – damages of
2005 usage - in 2005 money: 139 b$
Katrina, 2005: 81 b$
Pielke, Jr., R.A., Gratz, J., Landsea, C.W.,
Collins, D., Saunders, M., and Musulin, R.,
2008. Normalized Hurricane Damages in the
United States: 1900-2005. Natural Hazards
Review
Page 9
First task: Describing change
For doing so, we need long time series of (ideally) unchanging quality
(no improvement across time!)
This property is named “homogeneity”, the lack is “inhomogeneity”.
Thus, time series such as that one collected on Helgoland Roads
are of utmost importance.
These data are successfully used to describe change, but formal
detection and attribution studies are needed to assess the present
change of North Sea hydro- and ecodynamics.
Using Helgoland Roads data for
determining change
Schlüter et al. use Helgoland Roads and data
1975-2004.
They find a regime shift in 1987/88 and
conclude that this shift is driven by hydrometeorological forcing
First EOF of a series of hydroand ecodynamial parameters
Mostly Helgoland
Roads data
Schlüter M.H., A. Merico, K.H. Wiltshire, W. Greve and H. von Storch, 2009: A statistical analysis of climate variability and ecosystem response in the German Bight, Ocean Dyn
Using Helgoland Roads data for
determining change
Schlüter’s result raises a number of additional questions:
Was this just an event in an unending sequence of naturally occuring
“regime shifts”? (What “change character” has “regime shift”?)
What about the spatial representativity? (Merely a signal for Helgoland, for
Deutsche Bucht, or for the North Sea, the world ocean?)
How is the signal related to other change in the region?
The results underline not only the importance of
maintaining long-term monitoring programs but also
the need of homogeneous (model-based) analysis of
the changing regional conditions.
Reconstruction of marine „weather“ in the past
decades of years in in possible futures („scenarios“)
Extreme wind events simulated compared to
local observations
simuliert
Page 14
Sea surface temperature
Helgoland Roads
Elke Meyer, pers. comm.
The CoastDat-effort
at the Institute for Coastal Research@hzg
 Long-term, high-resolution reconstuctions (60 years) of present and 
recent developments of weather related phenomena in coastal
regions as well as scenarios of future developments (100 years)
 Northeast Atlantic and northern Europe
 Assessment of changes in storms, ocean waves, storm surges,
currents and regional transport of anthropogenic substances.
 Extension to other regions and to ecological parameters.
Applications
 many authorities with responsibilities for different aspects of the
German coasts
 economic applications by engineering companies (off-shore wind
potentials and risks) and shipbuilding company
 Public information
www.coastdat.de
CoastDat allows for a regional
contextualization of local Data (such as
helgoland Roads – see Scharfe‘s talk)
Variance 17%
Variance 70%
Climate Change of Scenarios
2030: temperature +1 ±0.4 degree; strong wind +2%±1% (winter);
Precipitation –10% summer, +10% winter (±5%);
2085: temperatures +3 ±1.2 degree; strong wind +8%±4%; (winter)
precipitation –30% summer, +30% winter (±10%);
External users
 More than 60 users
Mostly in Europe (Germany)
but also China and USA
 Diverse users
50% commerical (e.g., Swiss Re, Deltares,
Flensburger Shipbuilding),
25% authorities
25% scientific users
 Various applications
Optimal ship design
Planning and design of offshore wind energy
Marine energy
Assessment of pollution risks and changes
(chronic oil pollution, dispersion of lead)
Security of shipping
Using CoastDart wind for planning of
Off-shore wind parks
Long-term ecosystem trends
Algal Biomass (Chlorophyll-a)
German Bight March 2003
observed at Helgoland
Model constructed for CoastDateco,
a reconstruction of ecological states for
1962-2011
MERIS data
Model result (Chla)
First building blocks for CoastDateco
adaptive
cell size
Algal community structure
Variability in plankton
dynamics at Helgoland
Roads
Model validation using
AWI/Senckenberg data
Diatom biomass
data
model
Change is mostly described
- Hydrodynamic/ meteorological change: 1948-today in space-time detail, model
based analysis
- Ecodynamic change: local time series, first building blocks of model based analysis
- Ongoing monitoring in place (BSH, BAW, COSYNA etc.)
Is the change beyond normal variations? (Detection)
If so, what are the most plausible causes? (Attribution).
Regional detection
Sea level: Rise, intermittendly accelerated
SST: warming, accelerated increase
Storms: decadal variability
Species: additional warm-water species,
Loss of cold-water species
1.
Long records available in the German Bight, but
mostly contaminated by non-climatic signals in
ports and estuaries.
2.
Increase of about 20 cm/100 a
3.
No robust recent acceleration identified so far
No dedicated dection studies known, but
more results may become available from
the Mini-IPCC assessment NOSCCA due
in 2014 (or so).
Estimated regional sea level in the German Bight
Regional attribution
The issue is deconstructing a given record with the intention to identify „predictable“
components.
„Predictable“
-- either natural processes, which are known of having limited life times,
-- or man-made processes, which are subject to decisions (e.g., GHG, urban effect)
For global and regional temperatures, this has been done, and the ongoing
warming can not be explaining without considering elevated levels of GHG
concentrations as a key cause.
Regional attribution
Not systematically pursued on regional and local scales (see Mini-IPCC Report on
Baltic Sea Climate Change knowledge, BACC).
Regional manifestations of climate change
- enhanced concentrations of greenhouse gases
- reduction of industrial aerosols
- effect of changing land-use (e.g., urban effects)
So far no tools available for described of possible regional signals of change in
recent decades related to land use change and diminished aerosol loads.
Local changes
- Import of alien species; pollution, fishing and other uses
- Changing morphodynamic conditions (storm surges in Hamburg, Bremen etc.)
State of assessing regional change
Describing change:
Great scientific and operational progress
Discrimination between normal and externally forced changes:
Some scientific progress, but also claims-making without proper statistical
background
Attributing external causes :
Very little scientific efforts, but lots of
interest- and value-lead speculations
reflecting the politicization of the
environmental debate. (Some of which
may be overcome, some is intrinsically
political.)
Maybe better
results in
theforthcoming
NOSCCA report
There is lots of change in the German
Bight and in Northern Germany.
It raises concern among public and
stakeholders, generates excitement and
premature finger-pointing to causes and
causers in the public discourse.
Thus, cool scientific analysis is needed.
The latter needs more focus.